RELATIVE INFLUENCE OF PARENTS. 235 



female. As this physiological exposition, on which 

 the theory is based, is a pure assumption, in direct 

 conflict with the known facts of embryology, the essay 

 may be passed without further comment. 



A modified form of this theory has been elaborated 

 by Mr. Walker, 1 who draws most of his illustrations 

 from the human family ; and, more recently, Mr. Or- 

 ton a has advanced the same theory, in its applications 

 to stock-breeding. 



As a large proportion of modern writers on the 

 physiology of breeding have quoted the arguments 

 of Walker and Orton with approval, their theories 

 have assumed an importance that is not warranted by 

 their real merits. 



Mr. Walker enunciates his first law as follows : 

 "Where both parents are of the same variety, . . . 

 one parent communicates the anterior part of the head 

 (and I believe the upper middle part also), the osseous 

 or bony part of the face, the forms of the organs of 

 sense (the external ear, under lip, lower part of the 

 nose, and eyebrows, being often modified), and the 

 whole of the internal nutritive system (the contents of 

 the trunk, or the thoracic and abdominal viscera, and 

 consequently the form of the trunk itself, in so far as 

 that depends upon its contents). The resemblance to 

 that parent is, consequently, found in the forehead 

 and the bony parts of the face, as the orbits, cheek- 

 bones, jaws, chin, and teeth, as well as the shape of 

 the organs of sense, and the tone of the voice. . . . 

 The other parent communicates the posterior part of 



1 " On Intermarriage," 1839. 



2 " On the Physiology of Breeding," two lectures, 1855. 



